Hello, I am new to the forum and this is my first post. Unfortunately, I need to go straight to a problem rather than socialize. My apologies for that...

My son's '97 Lariat (75K miles) has a 5.4L with a terrible knock that seems to be isolated to one cylinder. He came to my house to change the oil and after draining the crankase we pulled off the filter and I noticed a gush of oil. It appeared as though oil was trapped above the filter. He may have let the oil go a little longer than I would have but not long enough to cause a major problem. So we finished the oil change and started the motor to look for leaks. We got a lound knock as soon as it started but it went away in a few seconds. I attributed the knock to the oil pressure getting high enough to lube the top end. After letting it idle for a bit he took the truck for a short drive. All looked OK. The next day he drove th truck to work and on the way home the oil pressure guage started to fluctuate wildly and the knock came back. He brought the truck home and we have tried all kinds of troubleshooting to locate the cause of the knock. I drove the truck myself and noticed that as the knock increases, the truck loses power and will not accelerate beyond around 2500 rpms.

I finally tok the truck to a local mechanic who didn't even raise the hood. After listening to the knock he said he had heard it many times before. He said it has spun a bearing and would require an engine replacement. Evidently an overhaul is more trouble and expensive than a swap.

Does anyone have any ideas on how I should proceed? Get a second opinion?...maybe from a Ford dealership?

 

as for the oil pressure gauge fluxuating couldbe oil pressure switch down buy the oil filter appx 10.00 from napa. 10min to change hope this helps also if you live in a cold climate put a magnet type heater on the oil pan not on the bottom but on the front slope that is what i did and it helps.

 

I wouldn't write the motor off that fast, get a second opinion. A spun bearing is rarely an intemittent thing. Are there any engine codes?

 

Have you concidered that the oil pump might be going out ? Who knows, might be worth a shot.

Oh, and I dont trust mechanics that immediately say that you need a new motor. I took my truck to ford because of a knock and they said it needed a new motor and radiator and just about everything under the hood should be replaced. Utter and complete B.S ! All my truck needed was new exhaust as it had a broken piece of ceramic bouncing arround in one of the cats. They were completely incompetant or complete liars, one of the two. BTW, thats why I always do my own work ! OK.....sorry about the rant.

 

Yeah mine did the same thing, it knocked like a bugger when it was cold outside. Plugged exhaust will do it.

 

Mine did the same thing in my V10. Problem was it was the spun rod bearing. It's a specific sound, and those that have heard it can identify it quickly. What brand of oil filter was it (just so i can stay away from it)? There is a significant amount of oil that comes out when you pull the filter, especially if its a 4x4 with the filter relocated cuz both the hoses are full of oil too. Did your cel come on? The knock was getting progressively louder on mine, and then i encountered the same oil pressure going haywire and the drop in power (youre running on 7 cylinders as the timing in that cylinder is off). A reman'd engine is much cheaper than rebuilding it. The ford garage told me that they set a threshold on costs and if the rebuild crosses that threshold, they choose to replace the engine, and he said they almost always replace. The bearings are different on every journal with only thousandsth of an inch difference in each one, but different enough that if not done right it won't last long. I looked at a crank kit (crank, rods, bearings, pistons) and it was almost as much as a reman'd engine. These engines are astronomically expensive. The cheapest salvage motor i could find was 2800 bucks, and that had 2xx,xxxmi on it! You could probably get a reman'd engine and put it in yourself and save a ton of money.

 

Thanks to everyone for the quick responses to my post!

Yes I did get a check engine light. Below are the codes. I use a Car Chip so I can store the info on my PC. The oil filter was a Purolater. If I get this thing fixed, nothing but MotorCraft in the future! I haven't changed the oil and filter again yet. After reading some related post I think I may do that...just in case. I did pull the plugs and checked them for fouling, cracks, etc. I also checked the coils and boots and ended up replacing two sets. Another bit of info: I bought the truck used from a Ford dealer in '98 with 21K miles. After about a week it strated to have an intermittent problem when driving at about 2500rpm it sould start bucking, backfiring, and emitting a foul stench from the tailpipe. I took it to the dealer and they pulled the codes which indicated bad O2 sensor. They replaced it and the problem returned. After several attempts they finally replaced the PCM and since then it ran perfect. I'm not sure if I could be having more PCM problem again but thought I should mention it. Here's the most recent codes:

1) P0136 O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
2) P0156 O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)
3) P1131 Unknown Powertrain DTC (Manufacturer Controlled; Fuel and Air Metering)
4) P1151 Unknown Powertrain DTC (Manufacturer Controlled; Fuel and Air Metering)
5) P0171 System Too Lean (Bank 1)
6) P0174 System Too Lean (Bank 2)

Thanks again for the advice!!!

Curt